WIP - allowing apply operation to use plan file content about backend/state_store

Author: SarahFrench

internal/command/apply.go

@@ -210,16 +210,16 @@ func (c *ApplyCommand) PrepareBackend(planFile *planfile.WrappedPlanFile, args *
 			))
 			return nil, diags
 		}
-		if plan.Backend.Config == nil {
+		if plan.Backend.Config == nil && plan.StateStore.Config == nil {
 			// Should never happen; always indicates a bug in the creation of the plan file
 			diags = diags.Append(tfdiags.Sourceless(
 				tfdiags.Error,
 				"Failed to read plan from plan file",
-				"The given plan file does not have a valid backend configuration. This is a bug in the Terraform command that generated this plan file.",
+				"The given plan file does not have either a valid backend or state_store configuration. This is a bug in the Terraform command that generated this plan file.",
 			))
 			return nil, diags
 		}
-		be, beDiags = c.BackendForLocalPlan(plan.Backend)
+		be, beDiags = c.BackendForLocalPlan(plan)
 	} else {
 		// Both new plans and saved cloud plans load their backend from config.
 		backendConfig, configDiags := c.loadBackendConfig(".")

internal/command/meta_backend.go

@@ -302,19 +302,28 @@ func (m *Meta) selectWorkspace(b backend.Backend) error {
 // The current workspace name is also stored as part of the plan, and so this
 // method will check that it matches the currently-selected workspace name
 // and produce error diagnostics if not.
-func (m *Meta) BackendForLocalPlan(settings plans.Backend) (backendrun.OperationsBackend, tfdiags.Diagnostics) {
+func (m *Meta) BackendForLocalPlan(plan *plans.Plan) (backendrun.OperationsBackend, tfdiags.Diagnostics) {
 	var diags tfdiags.Diagnostics
 
-	f := backendInit.Backend(settings.Type)
-	if f == nil {
-		diags = diags.Append(fmt.Errorf(strings.TrimSpace(errBackendSavedUnknown), settings.Type))
-		return nil, diags
+	var b backend.Backend
+	var config plans.DynamicValue
+	if plan.StateStore.Config != nil {
+		// TODO - code for state_store
+	} else if plan.Backend.Config != nil {
+		settings := plan.Backend
+		config = plan.Backend.Config
+
+		f := backendInit.Backend(settings.Type)
+		if f == nil {
+			diags = diags.Append(fmt.Errorf(strings.TrimSpace(errBackendSavedUnknown), settings.Type))
+			return nil, diags
+		}
+		b = f()
+		log.Printf("[TRACE] Meta.BackendForLocalPlan: instantiated backend of type %T", b)
 	}
-	b := f()
-	log.Printf("[TRACE] Meta.BackendForLocalPlan: instantiated backend of type %T", b)
 
 	schema := b.ConfigSchema()
-	configVal, err := settings.Config.Decode(schema.ImpliedType())
+	configVal, err := config.Decode(schema.ImpliedType())
 	if err != nil {
 		diags = diags.Append(fmt.Errorf("saved backend configuration is invalid: %w", err))
 		return nil, diags